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01 Z71 - towed home with strap, trans doesn't engage.

Alloy25

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Alloy25 Enthusiast

Alloy25

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Hello.  My sister has a 2001 Silverado 1500 Z71.  My nephew and I were driving and the the quick connect for the heater core broke.  We towed it home with a strap and put the transmission in neutral and started towing about 35 mph.  After less than a mile the truck started making a grinding noise (engine off) so we pulled over and shifted the transfer case into neutral and continued towing.  

 

When I change the transfer case shift lever on the floor, i hear an electric motor actuate for about two seconds in each position.  Now when I put the truck in gear, it does nothing in drive or reverse.  When in Park, and the transfer case lever in any position, there is no "Park" and I can push the truck several feet.  

 

Did it burn up the clutches within a mile?  I'm puzzled that the Park doesn't work even if the trans was damaged.  Is the transfer case stuck in neutral?  Any other suggestions?

 

Any help is greatly appreciated.

Kevin

Alloy25 Enthusiast

Alloy25

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10 minutes ago, damnthetorpedoes said:

Sounds like the t case in still in neutral. Make sure the transmission is set to neutral when you make the transfer case gear change. 

Thanks for the suggestion.  My nephew showed me that the trans needed to be in neutral but still no luck.  

 

The the transfer case, GM 261. Even though the shift lever is on the floor, it still uses an electric motor to engage the gears?

JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted
42 minutes ago, Alloy25 said:

Thanks for the suggestion.  My nephew showed me that the trans needed to be in neutral but still no luck.  

 

The the transfer case, GM 261. Even though the shift lever is on the floor, it still uses an electric motor to engage the gears?

Sorry to be the bearer of bad news, but I think this is what happened: If you place the transfer case in neutral. The problem with towing automatic transmission vehicles, is that the transmission is not operating, therefore the pump is not pumping fluid throughout the tranny. This results in melted seals & seized brass bushings, because the output shaft is turning, but no oil is present. However, the transfer case is located after the tranny. Placing the transfer case in neutral will disengage the tranny from the drivetrain, thinking you did it too late. Other way would have been to disconnect drive shaft.

redwngr Senior Enthusiast

redwngr

Posted
Posted
50 minutes ago, Alloy25 said:

Thanks for the suggestion.  My nephew showed me that the trans needed to be in neutral but still no luck.  

 

The the transfer case, GM 261. Even though the shift lever is on the floor, it still uses an electric motor to engage the gears?

Front axles still engaged by the  electric actuators. 

 

There is an explanation about 'dolly towing' in the owners manuals. 

 

This is from a 2004 manual:

 

Two-Wheel-Drive Vehicles
Two-wheel-drive vehicles should not be towed with the rear wheels on the ground. Two-wheel-drive transmissions have no provisions for internal lubrication while being towed.
Two-wheel-drive vehicles can be dolly towed with the front wheels on the ground provided that the wheels are straight and the steering column has been locked.

 

Four-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle:
1. Drive the vehicle up onto the tow dolly.
2. Shift an automatic transmission to PARK (P), or a manual transmission to FIRST (1).
3. Turn the engine off, but leave the ignition on.
4. Firmly set the parking brake.
5. Securely attach the vehicle being towed to the tow dolly. 

6. Shift the transfer case to NEUTRAL.

See Four-Wheel Drive on page 2-35 for the proper procedure to select the neutral position for your vehicle.
7. Release the parking brake only after the vehicle being towed is firmly attached to the towing vehicle.
8. Turn the ignition off and lock the steering column. 

 

{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer case into NEUTRAL can cause your vehicle to roll even if the transmission is in Park (P) for
an automatic transmission, or if your vehicle is in gear, for a manual transmission. You or others could be injured. Make sure the parking
brake is firmly set before you shift the transfer case to NEUTRAL.

  • 2 weeks later...
Alloy25 Enthusiast

Alloy25

Posted
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I appreciate all the responses.  Took the truck to a transmission mechanic.  The truck has around 275,000 miles on it.  He said that the 2000 model and year newer, the transfer case uses magnesium aluminum alloy for the housing and it's a little softer and lighter than aluminum.  In combination with the high mileage, he showed me where part of the oil pump rubbed a hole in the case (at the bottom, towards the back) and all the oil drained out except for a few ounces.  Getting the rear transfer case housing and rebuild for $1000.

 

He showed me where the previous person who worked on it added way too much silicone to seal the case.  Silicone clogged up the oil pump sump at the bottom.  The transfer case worked for the last 7 years at least. 

 

He said that the clutches should be fine after only a mile and if it was around 20-30 miles it would have been a problem.  

Alloy25 Enthusiast

Alloy25

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The other issue with the truck is that when i drove it home on the interstate several weeks ago with around 1200 lbs in the bed, the transmission fluid hot light came on.  Pushed a little fluid out of the vent at the top which hit the exhaust and smoked a little on the right side.  Pulled over and let it cool.  Did it again about 30 miles later.  Drove fine for 2 week around town.  Coolant and transmission fluid was at the correct level.  Replaced the thermostat earlier in the week because the truck was running too cool and it was sticking open.  

 

Hopped on the interstate last week (when all the above issues occurred) and it spewed quite a bit of fluid out the top of the vent on the transmission (before the quick connect broke).  This time it happened, no lights came on the last 2 times.  We noticed when the transmission is about to spew fluid, the torque converter will unlock and start shifting up and down.  Took only 10 miles this time, with no load in the truck.

 

Having the transmission guy troubleshoot this, but won't have the transfer case finished until later today so he can test drive it.  He said possible torque converter issue not fully locking and building up heat.  Though he said this was unlikely since there wasn't any discoloration of the paint on the TC.  Possibly some valve issue inside the transmission but hasn't gotten that far yet.

 

Transmission was rebuilt about 5 years ago.  

 

Any suggestions?

 

Thanks.

 

 

intheburbs Enthusiast

intheburbs

Posted
Posted

The transmission pump is on the input shaft of the transmission.  For the mile you towed it, the transmission was rotating without any fluid being circulated.  I'd be concerned that damage was done to the tranny.  Make sure it gets checked out thoroughly.

Alloy25 Enthusiast

Alloy25

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Picked up the truck today.  There was no damage to the transmission from towing it a mile with the transfer case in gear.  He said around 20-30 miles there would be an issue.

 

Ended up rebuilding the transfer case with a new rear housing since part of the oil pump rubbed a hole in the case and all the fluid drained out.

 

Replaced torque converter, TC solenoid, and TC valve and inspected the transmission.  The transmission shop that rebuilt the transmission about 5 years ago installed the TC valve backwards.  He was surprised it would even lock up in overdrive.  the TC has been slipping for awhile and finally got so bad it was overheating.  

 

Quick connect to the heater core broke.  Everything happened within a half hour of each other.  Just a series of unfortunate events...

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